Organoruthenium carbide complexes as precatalysts for olefin metathesis

ABSTRACT

Embodiments in accordance with the present invention encompass an organoruthenium compound of the formula (I) or formula (II):Wherein X, L, R1, R2, R3, R4, R5, Ar1 and Ar2 are as defined herein. Also disclosed herein are the use of organoruthenium compound of formula (I) or formula (II) as (pre)catalysts for the olefin metathesis reactions, as well as to the process for carrying out the olefin metathesis reaction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.17/024,778, filed Sep. 18, 2020, now allowed, which claims the benefitof U.S. Provisional Application No. 62/901,860, filed Sep. 18, 2019,which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a series of organoruthenium carbidecomplexes, their use as (pre)catalysts in the metathesis reaction aswell as the process for carrying out the metathesis reaction. Morespecifically, the present invention relates to a series oforganoruthenium carbides which when activated under suitable conditionsexhibit improved catalytic activity for a wide range of metathesisreactions. This invention also relates to methods of making thesecompounds. Accordingly, the compounds of this invention find utility asprecatalysts for carrying out a variety of olefin metathesis reactions,including ring-opening metathetic polymerization (ROMP), among others.

Description of the Art

The metathesis of olefins is an important tool in the organic synthesis(Handbook of Metathesis, Vol. I-III, Grubbs, R. H., ed.; Wiley-VCH,2003).

Many ruthenium complexes actively catalyzing the metathesis of olefinsare well known in the art (see, for example, Vougioukalakis, G. C.;Grubbs, R. H. Chem. Rev. 2010, 110, 1746). The third generationcomplexes (such as Gru-III, Ind-III) were shown to be highly useful(pre)catalysts of the ring-opening metathetic polymerization (ROMP)reaction.

The third-generation catalysts initiate the metathesis reactions verypromptly, whereas, in some metathesis applications, such as mold ROMPpolymerization, it is advantageous to use a (pre)catalyst that does notinitiate the reaction immediately after adding it to the substrate butonly after an appropriate initiation by chemical agents, temperature orlight. The complexes characterized by delayed initiation are oftentermed “dormant catalysts” (Monsaert, S.; Vila, A. L.; Drozdzak, R.; VanDer Voort, P.; Verpoort, F., Chem. Soc. Rev., 2009, 38, 3360; R.Drozdzak, N. Nishioka, G. Recher, F. Verpoort, Macromol. Symp. 2010,293, 1-4). Exemplary “dormant catalysts” are the complexes A-F, as wellas the recently obtained P-1 and P-2 (Pietraszuk, C.; Rogalski, S.;Powala, B.; Mitkiewski, M.; Kubicki, M.; Spolnik, G.; Danikiewicz, W.;Wozniak, K.; Pazio, A.; Szadkowska, A.; Kozlowska, A.; Grela, K., Chem.Eur. J, 2012, 18, 6465-6469).

The co-pending PCT patent application, PCT/IB2019/054879, filed Jun. 11,2019 discloses various other organo-ruthenium precatalysts useful forROMP.

The mold ROMP polymerization allows obtaining finished articles.Dicyclopentadiene is one of the monomers frequently used for the moldpolymerization. Polydicyclopentadiene, being obtained by polymerizationof dicyclopentadiene, features, inter alia, a low moisture absorption aswell as resistance to stress and high temperature. This is why parts ofvehicles and specialized containers for the chemical industry are moreand more frequently manufactured by the (mold) ROMP polymerization ofdicyclopentadiene.

U.S. Pat. No. 9,328,132 B2 addresses some of these deficiencies faced bythe art in providing more robust “dormant catalysts” for olefinmetathesis reactions, pertinent portions of which are incorporatedherein by reference. However, there is still a need for improved“dormant catalysts” which can be activated under desirable ROMPpolymerization conditions and based on the intended end applications.

Accordingly, it is an object of this invention to provide a series ofimproved “dormant catalysts.”

It is also an object of this invention to provide processes for thepreparation of such organoruthenium dormant catalysts as disclosedherein.

Other objects and further scope of the applicability of the presentinvention will become apparent from the detailed description thatfollows.

From the viewpoint of practical industrial applications, it is ofextreme importance that the (pre)catalysts are stable in the presence ofoxygen as well as moisture during their use in the metathesis reaction.Development of stable and active (pre)catalysts for metathesis ofolefins as reported in the literature allowed to broaden significantlythe scope of possible uses of this transformation. Nevertheless, thesecomplexes are still prepared and used in metathesis reactions inatmosphere of inert gas, in dry solvents, since their stability againstoxygen and moisture is limited.

Surprisingly, it has now been found that the ruthenium complexesdepicted by the formula (I) are stable in the presence of air andmoisture.

wherein:

X is chlorine, bromine or iodine;

L is PR₃, where R is independently selected from the group consisting ofisopropyl, sec-butyl, tert-butyl, cyclohexyl, bicyclo(C₅-C₁₀)alkyl,phenyl, benzyl, isopropoxy, sec-butoxy, tert-butoxy, cyclohexyloxy,phenoxy and benzyloxy;

R₁ is selected from the group consisting of methyl, ethyl, isopropyl,sec-butyl, tert-butyl, substituted or unsubstituted cyclohexyl,substituted or unsubstituted phenyl, substituted or unsubstitutedbiphenyl and substituted or unsubstituted naphthyl;

Ar₁ is selected from the group consisting of substituted orunsubstituted phenyl, substituted or unsubstituted biphenyl andsubstituted or unsubstituted naphthyl;

wherein said substituents are selected from the group consisting ofmethyl, ethyl, iso-propyl, tert-butyl and phenyl; and

with the proviso that when X is chlorine R₁ is not2,4,6-trimethylphenyl.

It should be noted that a neutral “carbene” type heterocylic ligand islinked to ruthenium as depicted above in the compound of formula (I),which is a particular type of N-heterocyclic carbene (NHC) ligand.Various other NHC ligands that can also be used in forming various othercompounds of formula (I) are exemplified below.

It has been observed now that compounds of the formula (I) are verystable and can be stored, handled and used in metathesis reactionswithout any protective atmosphere of inert gas. Even more surprisingly,when X is iodine, the compounds of formula (I) are even more stable and“dormant” under ambient conditions. Even more advantageously, thecompounds of formula (I) are readily soluble in a variety of ring openmetathesis polymerizable (ROMP) cycloalkene monomers, and can be kept insolution for a number of days even up to ten days or longer attemperatures up to 35° C., thus find utility in a number of applicationsincluding for example photopatternable compositions, as 3D ink materialsand in nanoimprint lithography, just to mention a few.

Following their suitable activation, the compounds of the generalformula (I) actively catalyze the metathesis reactions carried out inthe presence of air. Moreover, the compounds of the general formula (I)actively catalyze the metathesis reactions only after being activated bychemical agents, and they are very hardly susceptible to thermalactivation. These properties enable excellent control of the time ofinitiating the reaction; such a property is very useful especially forthe ROMP-type reactions. It was unexpectedly observed that the compoundsof the general formula (I) allowed obtaining polycycloolefinic polymersvia the ROMP-type reaction carried out in the air, the amount of the(pre)catalyst used being significantly lower than that in the case ofusing classical complexes. Even an amount of 100 ppm (parts per million,by weight) of the complex according to the invention, the compounds ofthe general formula (I) or the compounds of the general formula (II),effectively catalyzes polymerization of a variety of cycloalkenes. Thus,this amount of the (pre)catalyst is less than half of that in the caseof the catalysts reported in the literature, see for example, M.Perring, N. B. Bowden Langmuir, 2008, 24, 10480-10487.

The compound of general formula (I) according to the invention, whereinX is chlorine, Ar₁ and R₁ are both 2,4,6-trimethylphenyl and L istricyclohexylphosphine, which is of the formula (IA) is known in theliterature.

1,3-bis(2,4,6-trimethylphenyl)-imidazolidin-2-ylidene-tricyclohexylphosphine-rutheniumcarbide dichloride (IA)

Accordingly, the compound of formula (IA) is expressly disclaimed fromthe compounds of general formula (I). It should further be noted thatPiers, et al., Organometallics 2012, 31, 5634-5637, have shown that thecompound of formula (IA) can be used to generate a phosphoniumalkylidene olefin metathesis catalyst photolytically using photoacidgenerator. The catalyst so generated is active for ring open metathesispolymerization of certain cycloalkenes. However, such reactions arecarried out in a solvent, and using a large amount of the catalyst, fromone to five mole percent of the catalyst. Therefore, such conditions arenot suitable for many applications, such as for example, as 3D inkmaterials for mass polymerization conditions.

Surprisingly, it has now been found that the compounds of formula (I)where X is iodine imparts unusually very high “dormant” effect on thecatalyst. Thus, the iodide compounds of formula (I) can be stable for along length of time even up to ten days or longer and can be made activeonly when subjected to suitable photoacid generators (PAG) and/orthermal acid generators (TAG). Even more interestingly, such compoundscan only be activated using PAGs or TAGs or such similar compounds whichgenerate a chloride ion. Thus offering unique advantages in usingcompounds of formula (I) and tailoring their use in many differentapplications. In addition, the possibility of affecting the propertiesof a (pre)catalyst by changing its ligands and, in consequence, thepossibility of optimal tuning its activity for a specific reaction, isextremely valuable. Accordingly it has now been observed that tuning ofthe ligands of the compounds of formula (I) can result in differentcatalytic activity as well as dormancy of the catalytic activity. Forexample, various substitutions of the N-heterocyclic carbene ligand(NHC) results in vastly different catalytic activity of the resultingcompound of formula (I). Thus, different compounds of formula (I) inaccordance with this invention can be tailored to meet the needs of theintended application.

Accordingly, there is provided the compounds of the general formula (I)in accordance with the present invention as described hereinabove asprecatalysts for the olefin metathesis reactions.

In some embodiments, the compound of the formula (I) according to thisinvention is having:

X is chlorine or iodine;

R₁ and Ar₁ are both substituted phenyl; and

L is PR₃, where each R is independently selected from the groupconsisting of isopropyl, sec-butyl, tert-butyl, cyclohexyl and phenyl.

In some other embodiments, the compound of the formula (I) according tothis invention is having:

X is chlorine or iodine;

L is PR₃, where R is independently selected from the group consisting ofisopropyl, sec-butyl, tert-butyl, cyclohexyl, phenyl, isopropoxy,sec-butoxy, tert-butoxy, cyclohexyloxy and phenoxy;

Ar₁ and R₁ are the same or different and each independently selectedfrom the group consisting of phenyl, 2,4,6-trimethylphenyl,2,6-dimethylphenyl; 4-methylphenyl, 2,4,6-triethylphenyl,2,6-diethylphenyl, 2,4,6-triisopropylphenyl and 2,6-diisopropylphenyl.

In yet some other embodiments, the compound of the formula (I) accordingto this invention is having:

X is chlorine;

R₁ and Ar₁ are independently selected from the group consisting ofphenyl,

2-methylphenyl, 2,4-dimethylphenyl, 2,6-dimethylphenyl,2,4,6-trimethylphenyl,

2-ethylphenyl, 2,4-diethylphenyl, 2,6-diethylphenyl,2,4,6-triethylphenyl,

2-isopropylphenyl and 2,6-diisopropylphenyl; and

L is tri(isopropyl)phosphine or tricyclohexylphosphine.

In yet some other embodiments, the compound of the formula (I) accordingto this invention is having:

X is chlorine;

R₁ and Ar₁ are independently selected from the group consisting ofphenyl,

2,4-dimethylphenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl,2,4-diethylphenyl,

2,6-diethylphenyl, 2,4,6-triethylphenyl, 2-isopropylphenyl and

2,6-diisopropylphenyl; and

L is tricyclohexylphosphine.

In yet some other embodiments, the compound of the formula (I) accordingto this invention is having:

X is iodine;

R₁ and Ar₁ are independently selected from the group consisting of

2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl,2,4,6-triethylphenyl

and 2,6-diisopropylphenyl; and

L is tricyclohexylphosphine.

In some other embodiments, the compound of the formula (I) according tothis invention is having:

X is iodine;

L is PR₃, where R is independently selected from the group consisting ofisopropyl, cyclohexyl and phenyl;

Ar₁ and R₁ are the same or different and each independently selectedfrom the group consisting of phenyl, 2,4,6-trimethylphenyl,2,4,6-triethylphenyl, 2,6-diethylphenyl, 2,4,6-triisopropylphenyl and2,6-diisopropylphenyl.

Representative non-limiting examples of the compound of the formula (I)may be enumerated as follows:

1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-ylidene-tricyclohexylphosphine-rutheniumcarbide dichloride (IB)

1,3-bis(2,4,6-trimethylphenyl)-imidazolidin-2-ylidene-tricyclohexylphosphine-rutheniumcarbide diiodide (IC)

1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-ylidene-tricyclohexylphosphine-rutheniumcarbide diiodide (ID)

The compounds of the general formula (I) can be prepared by any of theknown procedures in the art. For example, Carlson et al., disclose aprocedure for the preparation of the compound of formula (IA), whichinvolves reacting a suitable organoruthenium precursor compound to formthe compound of formula (IA), as more generically shown in Scheme I.

Scheme I shows the method in accordance with the present invention forthe preparation of the compounds of formula (I).

As shown in Scheme I, the compounds of formula (I) can be prepared by atleast two methods as illustrated, Route A or Route B. In Route A, asuitable organoruthenium precursor compound of formula (A) is reactedwith trans-2,3-dicarbomethoxymethylenecyclopropane at suitable reactionconditions. In the formula (A) X, L, Ar₁ and R₁ are as definedhereinabove. The reaction can be carried out at ambient or super-ambientconditions. Generally, such reactions are carried out in a suitableorganic solvent at a temperature from about 0° C. to about 100° C. orhigher. In some embodiments such reactions are carried out at atemperature from about 20° C. to about 50° C. Any of the solvents thatwould dissolve compound of formula (A) andtrans-2,3-dicarbomethoxymethylenecyclopropane can be employed in thisreaction. Suitable solvents include toluene, tetrahydrofuran,dichloromethane, dichloroethane, and mixtures in any combinationthereof.

In Route B, Scheme I, a compound of formula (B), where X, Ar₁ and R₁ areas defined hereinabove and R₆ is hydrogen or NO₂ is reacted with asuitable ligand, L, as defined above in the presence oftrans-2,3-dicarbomethoxymethylenecyclopropane at suitable reactionconditions. The reaction can again be carried out at ambient orsuper-ambient conditions. Generally, such reactions are carried out in asuitable organic solvent at a temperature from about 0° C. to about 100°C. or higher. In some embodiments such reactions are carried out at atemperature from about 20° C. to about 50° C. Any of the solvents thatwould dissolve compound of formula (B), ligand L andtrans-2,3-dicarbomethoxymethylenecyclopropane can be employed in thisreaction. Suitable solvents include toluene, tetrahydrofuran,dichloromethane, dichloroethane, and mixtures in any combinationthereof.

In another aspect of this invention there is also provided a compound offormula (II):

wherein:

X is chlorine, bromine or iodine;

L is PR₃, where R is independently selected from the group consisting ofisopropyl, sec-butyl, tert-butyl, cyclohexyl, bicyclo(C₅-C₁₀)alkyl,phenyl, benzyl, isopropoxy, sec-butoxy, tert-butoxy, cyclohexyloxy,phenoxy and benzyloxy;

R₂ and R₃ are the same or different and each independently selected fromthe group consisting of hydrogen, methyl, ethyl, linear or branched(C₃-C₆)alkyl, (C₆-C₁₀)aryl, methoxy, ethoxy, linear or branched(C₃-C₆)alkoxy, (C₆-C₁₀)aryloxy, —NHCO(C₁-C₆)alkyl,—NHCO-perfluoro(C₁-C₆)alkyl, —SO₂N((C₁-C₆)alkyl)₂ and —NO₂; or

R₂ and R₃ taken together with the carbon atom to which they are attachedto form a (C₃-C₇)cycloalkyl ring;

R₄ and R₅ are the same or different and each independently selected fromthe group consisting of hydrogen, methyl, ethyl and linear or branched(C₃-C₆)alkyl;

Ar₂ is selected from the group consisting of substituted orunsubstituted phenyl, substituted or unsubstituted biphenyl andsubstituted or unsubstituted naphthyl;

wherein said substituents are selected from the group consisting ofmethyl, ethyl, iso-propyl, tert-butyl and phenyl.

The compounds of formula (II) are also found to be very stable in thepresence of air and moisture and can be stored at ambient conditions fora longer period of time as a solution in a number of cycloalkenes whichundergo ring open metathesis polymerization, and yet can be activatedreadily by subjecting them to either photolytic or thermolyticconditions in the presence of either a photoacid generator or a thermalacid generator. Therefore, compounds of formula (II) also serve asexcellent (pre)catalysts for ring-opening metathetic polymerization(ROMP).

Accordingly, there is provided the compounds of the general formula (II)in accordance with the present invention as described hereinabove asprecatalysts for the olefin metathesis reactions.

In some embodiments, the compound of the formula (II) according to thisinvention is having:

X is chlorine or iodine;

each R₂, R₃, R₄ and R₅ is independently selected from the groupconsisting of methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl,tert-butyl and phenyl;

Ar₂ is substituted phenyl; and

L is PR₃, where each R is independently selected from the groupconsisting of isopropyl, sec-butyl, tert-butyl, cyclohexyl and phenyl.

In some other embodiments, the compound of the formula (II) according tothis invention is having:

X is chlorine;

R₂ and R₃ taken together with the carbon atom to which they are attachedto form a cyclopentyl, cyclohexyl or cycloheptyl ring;

each R₄ and R₅ is independently selected from the group consisting ofhydrogen, methyl, ethyl and iso-propyl;

Ar₂ is selected from the group consisting of phenyl, 2-methylphenyl,2,4-dimethylphenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl,2-ethylphenyl, 2,4-diethylphenyl, 2,6-diethylphenyl,2,4,6-triethylphenyl, 2-isopropylphenyl and 2,6-diisopropylphenyl; and Lis tri(isopropyl)phosphine or tricyclohexylphosphine.

In yet some other embodiments, the compound of the formula (II)according to this invention is having:

X is chlorine;

each R₂, R₃, R₄ and R₅ independently is methyl or ethyl;

Ar₂ is selected from the group consisting of phenyl, 2,4-dimethylphenyl,2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,4-diethylphenyl,2,6-diethylphenyl, 2,4,6-triethylphenyl, 2-isopropylphenyl and2,6-diisopropylphenyl; and

L is tricyclohexylphosphine.

In yet some other embodiments, the compound of the formula (II)according to this invention is having:

X is iodine;

each R₂, R₃, R₄ and R₅ independently is methyl or ethyl;

Ar₂ is selected from the group consisting of 2,6-dimethylphenyl,2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,4,6-triethylphenyl and2,6-diisopropylphenyl; and

L is tricyclohexylphosphine.

Representative non-limiting examples of the compound of the formula (II)may be enumerated as follows:

1-(2,6-diethylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide dichloride (IIA)

1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide dichloride (IIB)

1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide diiodide (IIC)

1-(2,6-diethylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide diiodide (IID)

1-(2,6-diisopropylphenyl)-3,3-dimethyl-2λ²-azaspiro[4.5]decylidene-triisopropylphosphineruthenium carbide dichloride (IIE)

1-(2,6-diisopropylphenyl)-3,3-dimethyl-2λ²-azaspiro[4.5]decylidene-triisopropylphosphineruthenium carbide diiodide (IIF)

1-(2,6-diethylphenyl)-3,5,5-trimethyl-3-phenylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide dichloride (IIG); and

1-(2,6-diethylphenyl)-3,5,5-trimethyl-3-phenylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide diiodide (IIH)

The compounds of the general formula (II) can be prepared by any of theknown procedures in the art, particularly, using similar procedures asused for the preparation of compounds of formula (I) describedhereinabove. More specifically, the compounds of formula (II) can beprepared in accordance with Scheme II starting with correspondingcompounds of formula (C) or (D) using either Route A or B.

The invention is related also to use of the compounds of the generalformula (I) or the compounds of the general formula (II) as definedhereinabove as (pre)catalysts in the metathesis reactions. In someembodiments, the compounds of the general formula (I) or the compoundsof the general formula (II) are used as (pre)catalysts in the reactionsof ring-closing metathesis, cross metathesis, homometathesis,alkene-alkyne type metathesis. In some other embodiments, the compoundsof the general formula (I) or the compounds of the general formula (II)are used as (pre)catalysts in the reaction of ring-opening metatheticpolymerization.

The invention concerns also a process for carrying out the metathesisreaction of olefins, wherein at least one olefin is contacted with acompound of the general formula (I) or the compounds of the generalformula (II) as a (pre)catalyst.

Generally, the metathesis reaction is carried out in an organic solvent.Any of the organic solvents that would allow such polymerizationreaction to be carried out can be used. Non-limiting examples of suchorganic solvents include dichloromethane, dichloroethane, toluene, ethylacetate and mixtures in any combination thereof.

In some embodiments, the metathesis reaction is carried out without anysolvent. In some other embodiments, the metathesis reaction is carriedout in the presence of a chemical activator. In general, the chemicalactivator is a Bronsted or Lewis acid or a halo-derivative of alkane orsilane. Non-limiting examples of such activators include hydrogenchloride, chlorotrimethylsilane or p-toluenesulfonic acid.

In some embodiments, the metathesis reaction is a ring-openingmetathetic polymerization of dicyclopentadiene.

In yet some other embodiments, the (pre)catalyst of the general formula(I) or the compounds of the general formula (II) is added in the solidform to dicyclopentadiene.

In one embodiment, the polymerization reaction is initiated by heatingthe mixture of dicyclopentadiene and the (pre)catalyst of the generalformula (I) or the compounds of the general formula (II) to atemperature of 30° C. or higher.

In some embodiments, the starting material contains at least 94 wt. % ofdicyclopentadiene.

In another embodiment, the metathesis reaction is carried out at atemperature of from 20 to 120° C. In yet another embodiment, themetathesis reaction is carried out in a period of from 1 minute to 24hours.

In some embodiments, the metathesis reaction is carried out in thepresence of an additive promoting formation of cross bonds.

In one embodiment, the metathesis reaction is carried out using theamount of the (pre)catalyst equal to or less than 1000 ppm.

Throughout the description of the invention and patent claims, if ppm(parts per million) units are used with relation to amount of substance,these are on a weight basis.

Since the inventors do not wish to be bound by any particular mechanismof catalysis, the “(pre)catalyst” term is used to indicate that thecompound according to the invention may be either the catalyst itself ora precursor of the active species being the actual catalyst.

The definitions of groups not defined below should have the broadestmeanings known in the art.

The term “optionally substituted” means that one or more hydrogen atomsof the group in question have been replaced with the specified groups,provided that such a substitution results in formation of a stablecompound.

The term “halo” or “halogen” represents an element selected from F, Cl,Br, I.

The term “alkyl” concerns a saturated, straight-chain or branched-chainhydrocarbon substituent having the specified number of carbon atoms. Thenon-limiting examples of alkyls are: methyl, ethyl, propyl, isopropyl,butyl, sec-butyl, tert-butyl, pentyl.

The term “alkoxy” concerns the alkyl substituent, as defined above,bound via an oxygen atom.

The term “perfluoroalkyl” represents the alkyl, as defined above,wherein all hydrogens have been replaced with halogen atoms, where thehalogen atoms may be identical or different.

The term “cycloalkyl” concerns a saturated mono- or polycyclichydrocarbon substituent having the specified number of carbon atoms. Thenon-limiting examples of a cycloalkyl substituent are cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl.

The term “alkenyl” concerns a non-cyclic, straight or branchedhydrocarbon chain having the specified number of carbon atoms andcontaining at least one carbon-carbon double bond. The non-limitingexamples of alkenyls are: vinyl, allyl, 1-butenyl, 2-butenyl.

The term “aryl” concerns an aromatic mono- or polycyclic hydrocarbonsubstituent having the specified number of carbon atoms. Thenon-limiting examples of aryl are: phenyl, mesityl, anthracenyl.

The term “heterocyclyl” concerns aromatic as well as non-aromatic cyclicsubstituents having the specified number of carbon atoms, wherein one ormore carbon atoms have been replaced with a heteroatom such as nitrogen,phosphorus, sulfur, oxygen, provided that there are no two directlyconnected oxygen or sulfur atoms in the ring. Non-aromatic heterocyclylscan contain from 4 to 10 atoms in the ring, whereas aromaticheterocyclyls must have at least 5 atoms in the ring. The benzo-fusedsystems also belong to heterocyclyls. The non-limiting examples ofnon-aromatic heterocyclyls are: pyrrolidinyl, tetrahydrofuranyl,dihydrofuranyl, tetrahydrothienyl, tetrahydropyranyl, dihydropyranyl,tetrahydrothiopyranyl, piperidinyl, morpholinyl, thiomorpholinyl,2-pyrrolinyl, indolinyl. The non-limiting examples of aromaticheterocyclyls are: pyridinyl, imidazolyl, pyrimidinyl, pyrazolyl,triazolyl, pyrazinyl, furyl, thienyl. The above-mentioned groups may bebound via a carbon atom or a nitrogen atom. For example, the substituentobtained by binding pyrrole may be either pyrrol-1-yl (N-bound) orpyrrol-3-yl (C-bound).

The term “neutral ligand” concerns a substituent having no electricalcharge, capable of coordinating to a ruthenium atom. The non-limitingexamples of such ligands are: N-heterocyclic carbene ligands, amines,imines, phosphines and oxides thereof, alkyl and aryl phosphites andphosphates, ethers, alkyl and aryl sulfides, coordinated hydrocarbons,haloalkanes and haloarenes. The term “neutral ligand” encompasses alsoN-heterocyclic compounds; their non-limiting examples are: pyridine,4-(N,N-dimethylamino)pyridine (DMAP), 3-bromopyridine, piperidine,morpholine, pyridazine, pyrimidine, pyrazine, piperazine,1,2,3-triazole, 1,3,4-triazole, 1,2,3-triazine and 1,2,4-triazine.

The term “anionic ligand” concerns the substituent capable toco-ordination with a metal center, bearing an electrical charge capableto compensate the charge of the metal center, wherein such acompensation may be complete or partial. The non-limiting examples ofanionic ligands are: fluoride, chloride, bromide or iodide anions,carboxylic acid anions, alcohol and phenol anions, thiol and thiophenolanions, (organo)sulfuric and (organo)phosphoric acid anions as well asanions of esters thereof.

The term “carbene” concerns a molecule containing a neutral carbon atomhaving the valence number of 2 and two non-paired valence electrons. Theterm “carbene” encompasses also carbene analogs, wherein the carbon atomis replaced with another chemical element such as: boron, silicon,nitrogen, phosphorus, sulfur. The term “carbene” relates particularly toN-heterocyclic carbene (NHC) ligands. The non-limiting examples of theNHC ligands are:

The following examples describe the procedures used for the preparationof the compounds of this invention. The following examples are onlyintended to illustrate the invention and to explain its particularaspects.

EXAMPLE 1

To a solution of dimethyl 3-methylenecyclopropane-1,2-dicarboxylate(0.613 g, 3.6 mmol, 1.8 equiv.) in dry, deoxygenated dichloromethane (20mL) complex (A-1) (1.698 g, 2 mmol, 1 equiv.) was added as solid. Themixture was refluxed under argon atmosphere for 2 h. After that time themixture was cooled down to rt. From that point all operations werecarried out in air atmosphere. Volume of the dichloromethane was reducedto ca. 5 mL and methanol (5 mL) was added. The remaining dichloromethanewas slowly removed using rotary evaporator and crystals formed werefiltered, washed with methanol (3×1 mL) and dried in vacuum. The titlecompound (IA) was obtained as yellow crystalline solid, 1.37 g (89%),and was characterized by NMR as follows:

¹H NMR (601 MHz, CDCl₃): 6.95 (s, 2H), 6.89 (s, 2H), 4.14-4.00 (m, 4H),2.54 (s, 6H), 2.49 (s, 6H), 2.34-2.26 (m, 6H), 2.24 (s, 3H), 1.92-1.84(m, 6H), 1.72-1.64 (m, 6H), 1.64-1.58 (m, 3H), 1.24-1.06 (m, 15H).

¹³C NMR (151 MHz, CDCl₃): 479.2, 212.6, 212.0, 138.3, 138.2, 138.0,137.9, 137.2, 136.8, 135.1, 129.3, 129.2, 128.4, 127.7, 126.1, 113.7,53.4, 52.0, 51.9, 50.9, 50.8, 31.1, 31.0, 29.3, 27.9, 27.8, 26.3, 21.2,20.9, 19.7, 18.7. ³¹P NMR (243 MHz, CDCl₃): 34.1.

EXAMPLE 2

To a solution of complex (B-1) (1.71 g, 2 mmol, 1 equiv.) in dry,deoxygenated dichloromethane (20 mL) tricyclohexylphosphine (0.673 g,2.4 mmol, 1.2 equiv.) was added as solid under argon atmosphere. Themixture was stirred for 10 min at rt and dimethyl3-methylenecyclopropane-1,2-dicarboxylate (0.681 g, 4 mmol, 2 equiv.).The mixture was refluxed under argon atmosphere for 3 h. After that timethe mixture was cooled down to rt. From that point all operations werecarried out in air atmosphere. Volume of the dichloromethane was reducedto ca. 5 mL and methanol (5 mL) was added. The remaining dichloromethanewas slowly removed using rotary evaporator and crystals formed werefiltered, washed with methanol (3×1 mL) and dried in vacuum. The titlecompound (IC) was obtained as orange crystalline solid, 1.61 g (84%),and was characterized by NMR as follows:

¹H NMR (601 MHz, CDCl₃): 6.93 (s, 2H), 6.84 (s, 2H), 4.19-4.11 (m, 2H),4.09-4.02 (m, 2H), 2.98-2.76 (br, 3H), 2.71 (s, 6H), 2.61 (s, 6H), 2.26(s, 3H), 2.23 (s, 3H), 1.95 (br, 6H), 1.75-1.60 (m, 9H), 1.26-1.08 (m,15H).

¹³C NMR (151 MHz, CDCl₃): 475.8, 211.4, 210.9, 138.1, 137.9, 137.8,137.7, 137.1, 135.8, 129.5, 129.4, 53.4, 52.5, 52.4, 51.6, 51.5, 33.9,33.8, 30.5, 27.8, 27.8, 26.4, 22.7, 21.1, 21.0, 20.8.

³¹P NMR (243 MHz, CDCl₃): 32.3.

EXAMPLE 3

To a solution of complex (B-2) (1.88 g, 2 mmol, 1 equiv.) in dry,deoxygenated dichloromethane (20 mL) tricyclohexylphosphine (0.673 g,2.4 mmol, 1.2 equiv.) was added as solid under argon atmosphere. Themixture was stirred for 10 min at rt and dimethyl3-methylenecyclopropane-1,2-dicarboxylate (0.442 g, 2.6 mmol, 1.3equiv.). The mixture was refluxed under argon atmosphere for 18 h. Afterthat time the mixture was cooled down to rt. From that point alloperations were carried out in air atmosphere. Volume of thedichloromethane was reduced to ca. 5 mL and methanol (5 mL) was added.The remaining dichloromethane was slowly removed using rotary evaporatorand crystals formed were filtered, washed with methanol (3×1 mL) anddried in vacuum. The title compound (ID) was obtained as orangecrystalline solid, 1.74 g (84%), and was characterized by NMR asfollows:

¹H NMR (601 MHz, CDCl₃): 7.38-7.30 (m, 1H), 7.29-7.20 (m, 3H), 7.18-7.10(m, 2H), 4.30-4.12 (m, 4H), 3.90 (septet, J=6.6 Hz, 4H), 2.75 (q, J=11.9Hz, 3H), 1.96-1.87 (m, 6H), 1.70-1.62 (m, 6H), 1.61-1.55 (m, 3H), 1.50(d, J=6.5 Hz, 5H), 1.31 (dd, J=12.1, 6.7 Hz, 11H), 1.26-1.02 (m, 23H).

¹³C NMR (151 MHz, CDCl₃): 471.2, 214.6, 214.1, 149.0, 147.7, 139.1,135.9, 129.4, 129.2, 124.6, 123.6, 55.3 (2C), 53.8 (2C), 53.4, 34.4,34.3, 30.7, 29.7, 28.2, 27.8, 27.7 (2C), 26.4, 26.2, 25.1, 23.4.

³¹P NMR (243 MHz, CDCl₃): 32.8.

EXAMPLE 4

To a solution of complex (D-1) (1.16 g, 2 mmol, 1 equiv.) in dry,deoxygenated dichloromethane (20 mL) triisopropylphosphine (0.497 mL,0.417 g, 2.6 mmol, 1.3 equiv.) was added followed by dimethyl3-methylenecyclopropane-1,2-dicarboxylate (0.442 g, 2.6 mmol, 1.3equiv.). The mixture was stirred at rt under argon atmosphere for 18 h.From that point all operations were carried out in air atmosphere.Volume of the dichloromethane was reduced to ca. 5 mL and methanol (5mL) was added. The remaining dichloromethane was slowly removed usingrotary evaporator and crystals formed were filtered, washed withmethanol (3×1 mL) and dried in vacuum. The title compound (IIA) wasobtained as yellow crystalline solid, 1.09 g (90%), and wascharacterized by NMR as follows: ¹H NMR (601 MHz, CD₂Cl₂): 7.38-7.33 (m,1H), 7.33-7.28 (2H), 2.85 (dq, J=14.7, 7.3 Hz, 2H), 2.73 (ddt, J=14.5,11.0, 7.3 Hz, 3H), 2.53 (dq, J=14.8, 7.4 Hz, 2H), 2.09 (s, 2H), 1.73 (s,6H), 1.38-1.30 (m, 24H), 1.17 (t, J=7.4 Hz, 6H).

¹³C NMR (151 MHz, CD₂Cl₂): 473.5, 265.7, 265.2, 142.7, 139.6, 129.0,126.6, 80.9 (2C), 58.7, 58.6, 52.50 (2C), 31.2, 29.1, 25.5, 22.5, 22.4,19.8, 14.9. ³¹P NMR (243 MHz, CD₂Cl₂): 40.6.

EXAMPLE 5

To a solution of complex (D-2) (1.51 g, 2.5 mmol, 1 equiv.) in dry,deoxygenated toluene (25 mL) triisopropylphosphine (0.621 mL, 0.521 g,3.25 mmol, 1.3 equiv.) was added followed by dimethyl3-methylenecyclopropane-1,2-dicarboxylate (0.553 g, 3.25 mmol, 1.3equiv.). The mixture was stirred at 80° C. under argon atmosphere for 18h. After that time the mixture was cooled down to rt. From that pointall operations were carried out in air atmosphere. Toluene wasevaporated in vacuum and the residue was re-dissolved in small amount ofdichloromethane (ca. 7.mL). Methanol (7.mL) was added anddichloromethane was slowly removed using rotary evaporator. Crystalsformed were filtered, washed with methanol (3×1.5 mL) and dried invacuum. The title compound (IIB) was obtained as yellow crystallinesolid, 1.32 g (84%), and was characterized by NMR as follows:

¹H NMR (601 MHz, C₆D₆): 7.20-7.17 (m, 2H), 7.15-7.12 (m, 1H), 3.26(septet, J=6.4 Hz, 2H), 2.68 (ddt, J=14.5, 10.8, 7.3 Hz, 3H), 1.93 (s,6H), 1.66 (s, 2H), 1.58 (d, J=6.3 Hz, 6H), 1.30-1.24 (m, 24H), 1.03 (s,6H).

¹³C NMR (151 MHz, C₆D₆): 472.2, 268.3, 267.8, 147.8, 137.1 (2C), 130.00,125.7, 79.8 (2C), 58.7 (2C), 52.3 (2C), 31.0, 30.2, 29.2, 27.7, 25.0,22.6, 22.5, 20.0. ³¹P NMR (243 MHz, C₆D₆): 39.8.

EXAMPLE 6

To a solution of complex (B-3) (1.89 g, 2.5 mmol, 1 equiv.) in dry,deoxygenated dichloromethane (25 mL) tricyclohexylphosphine (0.841 g, 3mmol, 1.2 equiv.) was added as solid under argon atmosphere. The mixturewas stirred for 10 min at rt and dimethyl3-methylenecyclopropane-1,2-dicarboxylate (0.553 g, 3.25 mmol, 1.3equiv.). The mixture was refluxed under argon atmosphere for 2 h. Afterthat time the mixture was cooled down to rt. From that point alloperations were carried out in air atmosphere. Volume of thedichloromethane was reduced to ca. 7 mL and methanol (7 mL) was added.The remaining dichloromethane was slowly removed using rotary evaporatorand crystals formed were filtered, washed with methanol (3×1.5 mL) anddried in vacuum. The title compound (IB) was obtained as yellowcrystalline solid, 1.81 g (85%), and was characterized by NMR asfollows:

¹H NMR (601 MHz, CDCl₃): 7.48-7.06 (m, 6H), 4.34-3.98 (m, 4H), 3.90-3.35(m, 4H), 2.30-2.19 (m, 3H), 1.89-1.80 (m, 6H), 1.65-1.00 (m, 48H).

¹³C NMR (151 MHz, CDCl₃): 476.2, 215.0, 214.4, 149.1, 147.8, 138.8,135.1, 129.3, 124.2, 123.5, 54.4, 53.7, 31.3, 31.2, 29.4, 29.3, 28.1,27.7, 27.6, 27.4, 26.3, 25.8, 23.4, 23.1.

³¹P NMR (243 MHz, CDCl₃): 35.4.

EXAMPLE 7

To a solution of complex (D-3) (1.1 g, 1.45 mmol, 1 equiv.) in dry,deoxygenated dichloromethane (15 mL) triisopropylphosphine (0.359 mL,0.301 g, 1.88 mmol, 1.3 equiv.) was added followed by dimethyl3-methylenecyclopropane-1,2-dicarboxylate (0.32 g, 1.88 mmol, 1.3equiv.). The mixture was stirred at rt under argon atmosphere for 18 h.From that point all operations were carried out in air atmosphere.Volume of the dichloromethane was reduced to ca. 5 mL and methanol (5mL) was added. The remaining dichloromethane was slowly removed usingrotary evaporator and crystals formed were filtered, washed withmethanol (3×1 mL) and dried in vacuum. The title compound (IID) wasobtained as orange crystalline solid, 0.945 g (83%), and wascharacterized by NMR as follows:

¹H NMR (601 MHz, CD₂Cl₂): 7.34-7.26 (m, 3H), 3.30-3.12 (m, 5H), 2.66(dq, J=14.9, 7.4 Hz, 2H), 2.11 (s, 2H), 1.87 (s, 6H), 1.41 (s, 6H),1.37-1.31 (m, 18H), 1.22 (t, J=7.4 Hz, 6H).

³¹P NMR (243 MHz, CD₂Cl₂): 36.

Although the invention has been illustrated by certain of the precedingexamples, it is not to be construed as being limited thereby; butrather, the invention encompasses the generic area as hereinbeforedisclosed. Various modifications and embodiments can be made withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A compound of formula II:

wherein: X is chlorine, bromine or iodine; L is PR₃, where R isindependently selected from the group consisting of isopropyl,sec-butyl, tert-butyl, cyclohexyl, bicyclo(C₅-C₁₀)alkyl, phenyl, benzyl,isopropoxy, sec-butoxy, tert-butoxy, cyclohexyloxy, phenoxy andbenzyloxy; R₂ and R₃ are the same or different and each independentlyselected from the group consisting of hydrogen, methyl, ethyl, linear orbranched (C₁-C₆)alkyl, (C₆-C₁₀)aryl, methoxy, ethoxy, linear or branched(C₁-C₆)alkoxy, (C₆-C₁₀)aryloxy, —NHCO(C₁-C₆)alkyl,—NHCO-perfluoro(C₁-C₆)alkyl, —SO₂N((C₁-C₆)alkyl)₂ and —NO₂; or R₂ and R₃taken together with the carbon atom to which they are attached to form a(C₃-C₇)cycloalkyl ring; R₄ and R₅ are the same or different and eachindependently selected from the group consisting of hydrogen, methyl,ethyl and linear or branched (C₁-C₆)alkyl; Ar₂ is selected from thegroup consisting of substituted or unsubstituted phenyl, substituted orunsubstituted biphenyl and substituted or unsubstituted naphthyl;wherein said substituents are selected from the group consisting ofmethyl, ethyl, iso-propyl, tert-butyl and phenyl.
 2. The compoundaccording to claim 1, wherein: X is chlorine or iodine; each R₂, R₃, R₄and R₅ is independently selected from the group consisting of methyl,ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl and phenyl;Ar₂ is substituted phenyl; and L is PR₃, where each R is independentlyselected from the group consisting of isopropyl, sec-butyl, tert-butyl,cyclohexyl and phenyl.
 3. The compound according to claim 1, wherein: Xis chlorine; R₂ and R₃ taken together with the carbon atom to which theyare attached to form a cyclopentyl, cyclohexyl or cycloheptyl ring; eachR₄ and R₅ is independently selected from the group consisting ofhydrogen, methyl, ethyl and iso-propyl; Ar₂ is selected from the groupconsisting of phenyl, 2-methylphenyl, 2,4-dimethylphenyl,2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2-ethylphenyl,2,4-diethylphenyl, 2,6-diethylphenyl, 2,4,6-triethylphenyl,2-isopropylphenyl and 2,6-diisopropylphenyl; and L istri(isopropyl)phosphine or tricyclohexylphosphine.
 4. The compoundaccording to claim 1, wherein: X is chlorine; each R₂, R₃, R₄ and R₅independently is methyl or ethyl; Ar₂ is selected from the groupconsisting of phenyl, 2,4-dimethylphenyl, 2,6-dimethylphenyl,2,4,6-trimethylphenyl, 2,4-diethylphenyl, 2,6-diethylphenyl,2,4,6-triethylphenyl, 2-isopropylphenyl and 2,6-diisopropylphenyl; and Lis tricyclohexylphosphine.
 5. The compound according to claim 1,wherein: X is iodine; each R₂, R₃, R₄ and R₅ independently is methyl orethyl; Ar₂ is selected from the group consisting of 2,6-dimethylphenyl,2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,4,6-triethylphenyl and2,6-diisopropylphenyl; and L is tricyclohexylphosphine.
 6. The compoundaccording to claim 1, which is:

1-(2,6-diethylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide dichloride.
 7. The compound according to claim 1,which is:

1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide dichloride.
 8. The compound according to claim 1,which is:

1-(2,6-diethylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide diiodide.
 9. The compound according to claim 1, whichis:

1-(2,6-diethylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide diiodide.
 10. The compound according to claim 1, whichis:

1-(2,6-diisopropylphenyl)-3,3-dimethyl-2λ²-azaspiro[4.5]decylidene-triisopropylphosphineruthenium carbide dichloride.
 11. The compound according to claim 1,which is:

1-(2,6-diisopropylphenyl)-3,3-dimethyl-2λ²-azaspiro[4.5]decylidene-triisopropylphosphineruthenium carbide diiodide.
 12. The compound according to claim 1, whichis:

1-(2,6-diethylphenyl)-3,5,5-trimethyl-3-phenylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide dichloride.
 13. The compound according to claim 1,which is:

1-(2,6-diethylphenyl)-3,5,5-trimethyl-3-phenylpyrrolidin-2-ylidene-triisopropylphosphineruthenium carbide diiodide.
 14. A process for carrying out a metathesisreaction of olefins, comprising contacting at least one olefin with thecompound of claim 1 as a precatalyst.
 15. The process according to claim14, wherein the metathesis reaction is carried out in an organicsolvent.
 16. The process according to claim 15, wherein the organicsolvent is selected from the group consisting of dichloromethane,dichloroethane, toluene, ethyl acetate and a mixture in any combinationthereof.
 17. The process according to claim 14, wherein the metathesisreaction is carried out in the presence of a chemical activator.
 18. Theprocess according to claim 17, wherein the chemical activator is aBronsted or Lewis acid or a halo-derivative of alkane or silane.
 19. Theprocess according to claim 14, wherein the metathesis reaction iscarried out in the presence of a photoacid generator.
 20. The processaccording to claim 14, wherein the metathesis reaction is carried out inthe presence of a thermal acid generator.